Study On The Car Bonnet With Air Conditioning Composite Molded By Die-casting And Forging Liquid

Vehicle air conditioning bonnet is a key component of automotive air conditioning,the structure is complex,and has high airtightness requirements of its intermediate cylindrical portion,produced by conventional pressure casting the products often present shrinkage defects,leading the product qualification rate is low. In recent years,with the rapid development of computer numerical simulation technology, making through simulation software simulate the entire die casting process,clearly presents the entire casting process and thus guides the actual production possible.Through simulating flow field of filling process and temperature field of solidification process of the original program by casting simulation software program of Anycasting. The original program was found filling instability,there are a lot of eddy current and volume of gas phenomenon,during solidification the temperature field was unbalance,the possibility of producing shrinkage of the cylindrical portion of the middle and tail parts is heavy large. By cutting the middle of the cylindrical casting parts of the original program found that there are a lot of shrinkage defects,and then verify the accuracy of the numerical simulation.For there are a lot of shrinkage defects of casting of the original program, the gating system and mold structure has been redesigned. The gate was changed two to one, increasing the distance between the two cavities, using mold cavity of cross arrangement and arc-shaped runner. Based on this, through Anycasting simulation found that the filling process of the casting is more stable under the new program, and volumes of gas vortex phenomenon has been greatly improved, solidification temperature field is also more reasonable. Then the orthogonal experiment was designed to optimize die casting process parameters,select three important factors that affect the quality of casting: the pouring temperature, injection speed, mold preheat temperature, made a three factors and three levels orthogonal experiment; Through range analysis found that three key factors influencing the quality of casting followed by primary to secondary as follows: pouring temperature, mold preheat temperature, injection speed;by further analysis of the test results obtained the optimal solution as follows: pouring temperature is 650 ℃, mold preheating temperature is 200 ℃, injection speed is 2.5m ? s-1. Two levels were added for each of these factors to study the influence of various factors on the quality of the casting.According to the forming process characteristics of liquid forging,the extrusion device was designed,after the completion of die-filling of the new program,extruding the liquid metal of the intermediate cylindrical portion, making it produce a small amount of plastic deformation and solidificate under pressure in order to get die castings of better quality. Through finite element software Deform simulate the plastic deformation of solidification process after die-filling of liquid forging obtain the metal flow pattern of liquid forging in forming process,the equivalent stress field of liquid forging,equivalent strain and temperature fields;The metal flow of liquid forging process helps reduce shrinkage defects.Actual casting production was carried according to the improved program,cutting in the middle of the cylindrical part to observe the macro and micro structure we found that shrinkage defects decreased a lot,reflects the advantages of composite molding of die-casting and forging liquid.